Overview
- 3I/ATLAS reached perihelion on Oct. 29 at roughly 1.4 AU from the Sun, inside Mars’s orbit, during a period of limited ground visibility near solar conjunction.
- A NASA Swift team led by Auburn University detected ultraviolet hydroxyl, a marker of water, indicating an estimated outgassing rate near 40 kg per second at a distance where most comets are typically inactive.
- NASA and ESA state there is no impact risk to Earth, with the closest approach expected around Dec. 19 at roughly 240–270 million kilometers.
- An international effort is observing the object with Hubble, the James Webb Space Telescope, TESS, Mars-orbiting spacecraft and other probes to capture data before and after perihelion.
- The International Asteroid Warning Network has scheduled a coordinated observing campaign from Nov. 27 to Jan. 27 to refine astrometry and continue monitoring of the third confirmed interstellar visitor and its unusual behavior.